Nekar Xenos <nek### [at] gmailcom> wrote:
> I was thinking of adding any particular infinity to itself.

In a sense, adding infinity to itself doesn't make any sense because
infinity is not a number. It's a concept used to describe an abstraction.

There are certain situations where you can use mathematical operators
on infinities as a kind of special notation.

Calculating limits is one situation where infinity-as-a-notation can be
useful.

For example, if lim(x->a) f(x) is infinity, and lim(x->a) g(x) is
infinity, then you can use the notation that lim(x->a) f(x)+g(x) =
infinity + infinity = infinity. In other words, since both f(x) and
g(x) approach infinity when x approaches a, you know that their sum
will also do so.

This doesn't mean that "infinity" is some kind of "special number" that
you can add or do special operations. It's not a number. As said, this
is just a notation you can use to make such calculations easier.

The same is true for multiplication. lim(x->a) f(x)*g(x) is also infinity.

This is also the reason why it's said that eg. "infinity - infinity" is
indetermined. It basically means that the notation system fails and
cannot be used to determine the correct result.

In other words, if it were lim(x->a) f(x)-g(x), the result depends on
what f(x) and g(x) are. You cannot know the answer only from knowing
that their individual limits go to infinity.

-- 
                                                          - Warp

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